Modular drilling reamer

ABSTRACT

The present invention provides a modular drilling reamer which includes a central tube, a drill bit base and a centralizer which are detachably connected to two opposite ends of the central tube respectively. The drill bit base has a first connecting hole for detachably connecting with the central tube and assembling holes for mounting single drill bits, scrapers and/or centralizing rollers. The centralizer has a second connecting hole for detachably connecting with the central tube. The modular drilling reamer provided by the present invention can be modular with various replaceable drill bits by connecting the central tube with the centralizer and the drill bit base. It is convenient to assemble and is applicable to various reaming sizes and operations by replacing the drill bit bases which are different in size or the drill bit base equipped with different drill bits.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of Hong Kong Short-term Patent Application No. 15100357.0 filed on Jan. 13, 2015; the contents of which are hereby incorporated by reference.

FIELD OF INVENTION

The present invention relates to a reamer, in particular to a modular drilling reamer.

BACKGROUND

Commonly used drilling reaming equipments are lever mechanical type, hydraulic type and centrifugal type, etc. However, the reaming size is restricted, and it is troublesome to replace worn parts for corresponding facilities because most of the worn parts, such as specific-sized drill bits, drill bit bases and centralizer, are permanently connected with the specific-sized central tubular body of the reamer having an inner cavity by welding or the worn parts form an single body with the central tubular body of the reamer. Thus it is difficult to exchange the worn parts. Especially, it is difficult to design a structure arrangement of drilling for reaming operation of a horizontal well with a medium/small diameter. For drilling diameter ranging from 12 inches to 60 inches, it is very difficult to design by using traditional reaming methods, due to limited reaming space.

SUMMARY OF THE INVENTION

In order to overcome the problems of the existing technology, the present invention provides a modular drilling reamer. The modular drilling reamer comprises a central tube, a drill bit base and a centralizer which are detachably connected to both ends of the central tube respectively. The drill bit base comprises a first connecting hole for detachably connecting with the central tube and assembling holes for mounting single drill bits, scrapers and/or centralizing rollers. The centralizer comprises a second connecting hole for detachably connecting with the central tube. Preferably, the drill bit base is a flange.

According to one embodiment of the present invention, the modular drilling reamer also comprises a bushing. The bushing is sheathed on the central tube, and both ends of the bushing are detachably and fixedly connected with the drill bit base and the centralizer respectively.

According to another embodiment of the present invention, one end of the first connecting hole and one end of the second connecting hole respectively comprise a first radial receiving portion and a second radial receiving portion which form clearances with the central tube. Both ends of the bushing extend into the first radial receiving portion and the second radial receiving portion respectively. Preferably, the first radial receiving portion and/or the second radial receiving portion are/is fixedly connected with the bushing via threaded connection and/or welding.

According to another embodiment of the present invention, the first connecting hole and/or the second connecting hole are/is detachably connected with the central tube through threaded connection.

According to another embodiment of the present invention, the drill bit base comprises fixing plates which are positioned on the outer surface of the first connecting hole and disposed along the longitudinal direction of the first connecting hole. Preferably, the quantity of the fixing plates equals to that of single drill bits, the scrapers and/or the centralizing rollers which are mounted on the drill bit base. Optionally, the fixing plates are right-angle triangle support plates. Preferably, each fixing plate comprises reinforcing ribs.

According to another embodiment of the present invention, a first sealing ring is installed between the bushing and the first connecting hole. A second sealing ring is installed between the bushing and the second connecting hole. Preferably, the bushing comprises a first annular groove for installing the first sealing ring and a second annular groove for installing the second sealing ring.

According to another embodiment of the present invention, the outer surface of the bushing is connected with the drill bit base via welding and/or threaded connection, and the outer surface of the bushing is also connected with the centralizer via welding and/or threaded connection. Preferably, the welding is intermittent welding.

According to another embodiment of the present invention, each assembly hole comprises a fixing block inside. One side surface of the fixing block forms a pressure-bearing slope. The width of the fixing block is gradually decreased from one end near the centralizer to another end away from the centralizer. Preferably, each fixing block is fixedly connected with the drill bit base through a fastening bolt.

According to a further embodiment of the present invention, the central tube comprises a central cavity which is communicated with an external fluid source. The drill bit base further comprises a nozzle assembling hole for assembling a nozzle. The nozzle is fixed inside the nozzle assembling hole. The nozzle comprises a check ring. Fluid in the central cavity and the nozzle is communicated through a hole and/or a pipeline penetrating through the central cavity and the nozzle.

Correspondingly, the present invention provides a modular drilling reamer which is convenient to be assembled and easily applicable to various reaming sizes and operations.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be described in detail by reference to the attached drawings and in conjunction with the embodiments. The contents as shown in the attached drawings are just for the purpose of illustrating the prevent invention, but not limiting the present invention.

FIG. 1 is a structural schematic diagram of the modular drilling reamer in one embodiment of the present invention.

FIG. 2 is a structural schematic diagram of the central tube in one embodiment of the present invention.

FIG. 3 is a cross-section diagram obtained along an A-A line in FIG. 1.

FIG. 4 is a vertical view of the drill bit base in one embodiment of the present invention.

FIG. 5 is a sectional view of the drill bit base in one embodiment of the present invention.

FIG. 6 is a structural schematic diagram of the bushing in one embodiment of the present invention.

FIG. 7 is a structural schematic diagram of the modular drilling reamer which is not installed with a drill bit in one embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

As shown in FIGS. 1-5, the present invention provides a modular drilling reamer. The modular drilling reamer comprises a cylindrical central tube, a drill bit base and centralizer. The cylindrical central tube acts as a main body of the reamer and has a diameter about 3″-10″. The drill bit base and the centralizer are detachably connected with two opposite ends of the central tube respectively by means of threaded connection, buckle type connection, plugging bolt type connection and the like. The shapes and sizes of the drill bit base and the centralizer match with the shape and size of the central tube and can refer to and employ existing technologies. After being assembled, the overall appearance of the reamer of the present invention is approximately the same as that of an integrally formed reamer in existing technology. According to the present invention, the drill bit base comprises a first connecting hole for detachably connecting with the central tube, and one or multiple assembling holes for mounting single drill bits 60, scrapers and/or centralizing rollers. The centralizer comprises a second connecting hole for detachably connecting with the central tube.

According to the demonstrative embodiment of the present invention as shown in FIG. 1, the central tube is connected with the drill bit base and the centralizer through threads. The central tube 10 of the reamer comprises a first thread 11 and a second thread 12. The first thread 11 is located at the upper half portion of the central tube 10 and the second thread 12 is located at the lower half portion of the central tube 10. The drill bit base 30 comprises a first connecting hole 21 for the central tube passing through, and assembling holes 32 for mounting single drill bits, scrapers and/or centralizing rollers. Both ends of the first connecting hole 21 are internally equipped with a threaded connection structure matched with the first thread 11 and an optional first radial receiving portion 31 for forming a clearance with the central tube. The centralizer 40 comprises a second connecting hole for the central tube passing through. Both ends of the second connecting hole respectively comprise a threaded connection structure matched with the second thread 12 and an optional second radial receiving portion for forming a clearance with the central tube. According to this embodiment, under the condition that the first thread 11 and/or the second thread 12 are/is male thread(s), the threaded connection structures of the first connecting hole and the second connecting hole are female threads correspondingly, and vice versa. According to other embodiments of the present invention, both ends of the central tube can be detachably connected with the drill bit base and the centralizer respectively through different manners, for example, the central tube and the drill bit base can be connected through threads, whereas the central tube and the centralizer can be connected through manners such as buckle type connection, plugging bolt type connection and other well-known connecting means. When adopting the buckle or plugging bolt type connection, multiple raised portions oppositely arranged in the radial direction or arranged in the circumferential direction are adopted to substitute for the first thread 11 or the second thread 12, whereas the first connecting hole and the second connecting hole are internally and correspondingly equipped with guide grooves and/or recessed portions configured to accommodate and lock the raised portions. Because the specific structures of the detachable connection mechanism adopted by the present invention are well-known, it is unnecessary to elaborate here.

As shown in FIG. 3, the drill bit base comprises a cylinder 22 composed of the first connecting hole 21, and optional fixing plates 23 located on the outer surface of the cylinder 22 and configured along the longitudinal direction of the cylinder 22 for a purpose of increasing the strength of the drill bit base. Each fixing plate 23 is of a right-angle triangle, wherein two right-angle sides are connected with the outer surface of the cylinder 22 and the drill bit base 30 respectively. Preferably, the fixing plate 23 may be also equipped with reinforcing ribs for improving the strength thereof. In this embodiment, four fixing plates 23 are configured, and in specific embodiments, the quantity of the fixing plates 23 is based on the purpose of meeting the preset strength requirement. Further, after the preset strength requirement is met, the quantity of the fixing plates 23 can be the same as or in correspondence with the quantity of the single drill bits, the scrapers and/or the centralizing rollers, that are configured on the drill bit base. The fixing plates 23 can be connected with the drill bit base 30 together through welding or other fixed connection manners, whereas one or multiple fixing plates 23 can be also integrally formed with the drill bit base in advance.

In order to increase the operation efficiency, preferably, the reamer can be also connected with an external fluid source or a fluid circulation system for a purpose of feeding and discharging fluid, such as water flow, gas flow and mud flow in a reaming operation process. For instance, in the reaming operation process, cyclically spraying and sucking the mud flow have a cooling effect and the mud flow rushing to a working surface of the drill bit can prevent a mud drum from occurring around the drill bit, and the mud flow will also flow to the hole walls, so that crushed rock debris will flow out of the hole in construction along with the mud through the clearance of the reamer, avoiding the situation that the rock debris is accumulated in front of the reamer owing to stagnant discharging of the rock debris. The reamer provided by the present invention may be connected and matched for use with a fluid source or a flow circulation system of the existing technology in conventional means (for example, an external pipeline or related fixing parts thereof) so as to improve the reaming operation efficiency.

In addition, as further shown in FIG. 4 and FIG. 5, the drill bit base 30 in this embodiment is a flange. In addition to the first radial receiving portion 31 and the assembling holes 32, preferably, the drill bit base 30 is also equipped with a nozzle assembling hole 33 configured to assemble an embedded nozzle 34, wherein the nozzle 34 can be detachably fixed in the nozzle assembling hole 33 through threads, and/or welding or other manners, and a check ring 35 can be also configured on the nozzle 34 and can be detachably fixed on the nozzle 34 through threads and/or welding or other manners. The central tube can be correspondingly equipped with a central cavity communicated with the external fluid source, wherein the central cavity and the nozzle 34 are communicated through fluid by means of a through hole and/or a pipeline (not shown) penetrating through both of which, and preferably, both ends of the through hole and/or pipeline can be configured and embedded into mutually adjacent portions of the drill bit base and the central tube, preventing from being impacted by fluid flow and materials drilled out. The fluid, such as mud or other materials from the external fluid source can be sprayed by the nozzle in the reaming operation to form a film on the inner wall of the drilled hole, and thus deformation of the drilled hole is avoided at a certain extent. Whereas, the structure of the centralizer 40 can be divided into a well-known wing shape or drum shape, of which the diameter of the biggest end should be matched with the diameter of the borehole formed before reaming, and should depend on the specific engineering requirements.

As shown in FIG. 6 and FIG. 7, in order to further strengthen the reamer, especially to strengthen the drill bit base and the centralizer, preferably, the modular drilling reamer comprises a bushing 50 which is sheathed on the central tube, wherein two opposite ends of the bushing are detachably and fixedly connected with the drill base bit and the centralizer respectively through threads and/or welding. Under the condition that the drill bit base and the centralizer comprise the first radial receiving portion and the second radial receiving portion, one end of the bushing 50 can be inserted and fixed in a clearance between the first radial receiving portion of the drill bit base and the central tube 10, and the other end of the bushing 50 can be inserted and fixed into a clearance between the second rail receiving portion of the centralizer 40 and the central tube 10. Therefore, the drill bit base and the centralizer are modular to form a single body through the bushing. Thus the overall strength between the drill bit base and the centralizer can be improved and the connecting strength and the shock resistance between the drill bit base as well as the centralizer and the central tube are also strengthened, and thus the connection is more stable and durable.

For a purpose of preventing leakage of the fluid from the external fluid source and well guiding the fluid flow, a first sealing ring is configured between the bushing 50 and the first connecting hole; and a second sealing ring is configured between the bushing 50 and the second connecting hole. Whereas, the bushing 50 is equipped with a first annular groove 51 for accommodating the first sealing ring and a second annular groove 52 configured to accommodate the second sealing ring. Therefore, the input fluid flow can flow through a preset path to produce an effect as required rather than flowing between the bushing and the central tube undesirably.

Since the threaded connection will generate clearance and is easy to loosen, for a purpose of preventing loosening, according to one preferred embodiment of the present invention, the outer surface of the bushing 50 and the bottom of the drill bit base 30 are additionally connected through welding or other reinforcing manners. Meanwhile, the outer surface of the bushing 50 may be further connected with the corresponding end portion of the centralizer 40 through welding or other well-known manners. Additional welding is made on a connecting portion 53 of the bushing and the drill bit base and a connecting portion 54 of the bushing and the centralizer in this embodiment, and preferably, such welding manner may employ intermittent welding.

The bushing 50 may be a disposable replaceable bushing, and specifically speaking, the centralizer 40 or the drill bit base and the bushing can be further permanently connected to form a single body through welding or other reinforcing manners after being coupled. After each project is accomplished or preset requirements are met, the centralizer or the drill bit base and the bushing can be dismantled integrally, and then connecting weld joints or connected portions therebetween can be further cut apart. The disposable intermediate bushing may be destructed, whereas the centralizer and the drill bit base can be reserved and repaired for future use.

When the modular drilling reamer provided by the present invention is directed to different reaming sizes, the whole drill bit base can be replaced, and a drill bit base matched with the structure arrangement of drilling is changed, wherein the changed drill bit base can be provided with a drill bit. Compared with the existing technology in which only the drill bit can be replaced, the modular drilling reamer provided by the present invention is superior in that not only the drill bits 60 can be replaced, but also the quantity of the drill bits and/or the distance between every two drill bits can be adjusted by a manner of replacing the drill bit base, so that the drill bit base can be better matched with the structure arrangement of the drilling. Generally speaking, a larger drill bit base has a larger space, and thus more drill bits can be selected to be mounted according to operation demands. According to the reamer provided by the present invention, the drill bit base may employ and connect with conventional drill bits of the existing technology, or may preferably employ a specific drill bit disclosed in PCT application WO2014/117416A1 (the Publication Date: Aug. 7, 2014) submitted by the applicant on Feb. 17, 2013, and the full text of this application is here incorporated by reference. Therefore, the assembling hole of the reamer provided by the present invention can be internally provided with the corresponding fixing block, wherein the pressure-loading slope is formed on one side surface of the fixing block, and the width of the fixing block is gradually decreased from one end close to the centralizer to another end away from the centralizer. The fixing bloc is detachably connected with the drill bit base through a well-known connecting mechanism. As shown in FIG. 1, the fixing block can be preferably separated and fixedly connected with the drill bit base through the fastening bolt, and thus the specific drill bit can be mounted or removed.

In conclusion, The modular drilling reamer provided by the present invention can be combined with various replaceable drill bits by connecting the central tube with the centralizer and the drill bit base. It is convenient to assemble and is applicable to various reaming sizes and operations by replacing the drill bit bases which are different in size or the drill bit base equipped with different drill bits (tooth inserting type or steel tooth type).

The preferred embodiments of the present invention are illustrated as above by reference to the attached drawings. Multiple transformation solutions can be made by those skilled in the art to realize the present invention, without departing from the scope and the essence of the present invention. For instance, partially indicated or described features of one embodiment can be used in another embodiment so as to obtain a further embodiment. Those stated above are just preferred feasible embodiments of the present invention and are thus not to limit the protection scope of the present invention. Equivalent transformations made by use of contents of the description and the attached drawings of the present invention should fall within the protection scope of the present invention. 

What is claimed is:
 1. A modular drilling reamer, comprising: a central tube; a drill bit base and a centralizer which are detachably connected to two opposite ends of the central tube respectively; wherein the drill bit base comprises a first connecting hole for detachably connecting with the central tube and assembling holes for mounting single drill bits, scrapers and/or centralizing rollers; the centralizer comprising a second connecting hole for detachably connecting with the central tube.
 2. The modular drilling reamer according to claim 1 further comprising a bushing sheathed on the center tube, wherein two opposite ends of the bushing are detachably and fixedly connected with the drill bit base and the centralizer respectively.
 3. The modular drilling reamer according to claim 2, wherein one end of the first connecting hole and one end of the second connecting hole respectively comprise a first radial receiving portion and a second radial receiving portion which form clearances with the central tube, and the two opposite ends of the bushing extend into the first radial receiving portion and the second radial receiving portion respectively.
 4. The modular drilling reamer according to claim 3, wherein the first radial receiving portion and/or the second radial receiving portion are/is fixedly connected with the bushing via threaded connection and/or welding.
 5. The modular drilling reamer according to claim 1, wherein the first connecting hole and/or the second connecting hole are/is detachably connected with the central tube via threaded connection.
 6. The modular drilling reamer according to claim 2, wherein the first connecting hole and/or the second connecting hole are/is detachably connected with the central tube via threaded connection.
 7. The modular drilling reamer according to claim 3, wherein the first connecting hole and/or the second connecting hole are/is detachably connected with the central tube via threaded connection.
 8. The modular drilling reamer according to claim 4, wherein the first connecting hole and/or the second connecting hole are/is detachably connected with the central tube via threaded connection.
 9. The modular drilling reamer according to claim 1, wherein the drill bit base comprises fixing plates which are located on outer surface of the first connecting hole and disposed along the longitudinal direction of the first connecting hole.
 10. The modular drilling reamer according to claim 2, wherein the drill bit base comprises fixing plates which are located on outer surface of the first connecting hole and disposed along the longitudinal direction of the first connecting hole.
 11. The modular drilling reamer according to claim 3, wherein the drill bit base comprises fixing plates which are located on outer surface of the first connecting hole and disposed along the longitudinal direction of the first connecting hole.
 12. The modular drilling reamer according to claim 4, wherein the drill bit base comprises fixing plates which are located on outer surface of the first connecting hole and disposed along the longitudinal direction of the first connecting hole.
 13. The modular drilling reamer according to claim 9, wherein quantity of the fixing plates equals to that of the single drill bits, the scrapers and/or the centralizing rollers mounted on the drill bit base.
 14. The modular drilling reamer according to claim 10, wherein quantity of the fixing plates equals to that of the single drill bits, the scrapers and/or the centralizing rollers mounted on the drill bit base.
 15. The modular drilling reamer according to claim 11, wherein quantity of the fixing plates equals to that of the single drill bits, the scrapers and/or the centralizing rollers mounted on the drill bit base.
 16. The modular drilling reamer according to claim 12, wherein quantity of the fixing plates equals to that of the single drill bits, the scrapers and/or the centralizing rollers mounted on the drill bit base.
 17. The modular drilling reamer according to claim 9, wherein the fixing plates are right-angle triangle support plates.
 18. The modular drilling reamer according to claim 10, wherein the fixing plates are right-angle triangle support plates.
 19. The modular drilling reamer according to claim 11, wherein the fixing plates are right-angle triangle support plates.
 20. The modular drilling reamer according to claim 12, wherein the fixing plates are right-angle triangle support plates.
 21. The modular drilling reamer according to claim 9, wherein the fixing plates comprises reinforcing ribs.
 22. The modular drilling reamer according to claim 10, wherein the fixing plates comprises reinforcing ribs.
 23. The modular drilling reamer according to claim 11, wherein the fixing plates comprises reinforcing ribs.
 24. The modular drilling reamer according to claim 12, wherein the fixing plates comprises reinforcing ribs.
 25. The modular drilling reamer according to claim 1, wherein the drill bit base is a flange.
 26. The modular drilling reamer according to claim 2, wherein the drill bit base is a flange.
 27. The modular drilling reamer according to claim 3, wherein the drill bit base is a flange.
 28. The modular drilling reamer according to claim 4, wherein the drill bit base is a flange.
 29. The modular drilling reamer according to claim 2, wherein a first sealing ring is installed between the bushing and the first connecting hole; and a second sealing ring is installed between the bushing and the second connecting hole.
 30. The modular drilling reamer according to claim 3, wherein a first sealing ring is installed between the bushing and the first connecting hole; and a second sealing ring is installed between the bushing and the second connecting hole.
 31. The modular drilling reamer according to claim 4, wherein a first sealing ring is installed between the bushing and the first connecting hole; and a second sealing ring is installed between the bushing and the second connecting hole.
 32. The modular drilling reamer according to claim 29, wherein the bushing comprises a first annular groove for installing the first sealing ring and a second annular groove for installing the second sealing ring.
 33. The modular drilling reamer according to claim 30, wherein the bushing comprises a first annular groove for installing the first sealing ring and a second annular groove for installing the second sealing ring.
 34. The modular drilling reamer according to claim 31, wherein the bushing comprises a first annular groove for installing the first sealing ring and a second annular groove for installing the second sealing ring.
 35. The modular drilling reamer according to claim 2, wherein outer surface of the bushing is connected with the drill bit base via welding and/or threaded connection, and the outer surface of the bushing is also connected with the centralizer via welding and/or threaded connection.
 36. The modular drilling reamer according to claim 3, wherein outer surface of the bushing is connected with the drill bit base via welding and/or threaded connection, and the outer surface of the bushing is also connected with the centralizer via welding and/or threaded connection.
 37. The modular drilling reamer according to claim 4, wherein outer surface of the bushing is connected with the drill bit base via welding and/or threaded connection, and the outer surface of the bushing is also connected with the centralizer via welding and/or threaded connection.
 38. The modular drilling reamer according to claim 4, wherein the welding is intermittent welding.
 39. The modular drilling reamer according to claim 35, wherein the welding is intermittent welding.
 40. The modular drilling reamer according to claim 36, wherein the welding is intermittent welding.
 41. The modular drilling reamer according to claim 37, wherein the welding is intermittent welding.
 42. The modular drilling reamer according to claim 1, wherein each the assembling hole comprises a fixing block inside, one side surface of the fixing block forming a pressure-bearing slope, width of the fixing block is gradually decreased from one end close to the centralizer to another end away from the centralizer.
 43. The modular drilling reamer according to claim 2, wherein each the assembling hole comprises a fixing block inside, one side surface of the fixing block forming a pressure-bearing slope, width of the fixing block is gradually decreased from one end close to the centralizer to another end away from the centralizer.
 44. The modular drilling reamer according to claim 3, wherein each the assembling hole comprises a fixing block inside, one side surface of the fixing block forming a pressure-bearing slope, width of the fixing block is gradually decreased from one end close to the centralizer to another end away from the centralizer.
 45. The modular drilling reamer according to claim 4, wherein each the assembling hole comprises a fixing block inside, one side surface of the fixing block forming a pressure-bearing slope, width of the fixing block is gradually decreased from one end close to the centralizer to another end away from the centralizer.
 46. The modular drilling reamer according to claim 42, wherein each of the fixing blocks is fixedly connected with the drill bit base through a fastening bolt.
 47. The modular drilling reamer according to claim 43, wherein each of the fixing blocks is fixedly connected with the drill bit base through a fastening bolt.
 48. The modular drilling reamer according to claim 44, wherein each of the fixing blocks is fixedly connected with the drill bit base through a fastening bolt.
 49. The modular drilling reamer according to claim 45, wherein each of the fixing blocks is fixedly connected with the drill bit base through a fastening bolt.
 50. The modular drilling reamer according to claim 1, wherein the central tube comprises a central cavity communicated with an external fluid source; and the drill bit base further comprises a nozzle assembling hole for assembling a nozzle, the nozzle being fixed inside the nozzle assembling hole, the nozzle comprising a check ring; wherein fluid in the central cavity and the nozzle is communicated through a hole and/or a pipeline penetrating through the central cavity and the nozzle.
 51. The modular drilling reamer according to claim 2, wherein the central tube comprises a central cavity communicated with an external fluid source; and the drill bit base further comprises a nozzle assembling hole for assembling a nozzle, the nozzle being fixed inside the nozzle assembling hole, the nozzle comprising a check ring; wherein fluid in the central cavity and the nozzle is communicated through a hole and/or a pipeline penetrating through the central cavity and the nozzle.
 52. The modular drilling reamer according to claim 3, wherein the central tube comprises a central cavity communicated with an external fluid source; and the drill bit base further comprises a nozzle assembling hole for assembling a nozzle, the nozzle being fixed inside the nozzle assembling hole, the nozzle comprising a check ring; wherein fluid in the central cavity and the nozzle is communicated through a hole and/or a pipeline penetrating through the central cavity and the nozzle.
 53. The modular drilling reamer according to claim 4, wherein the central tube comprises a central cavity communicated with an external fluid source; and the drill bit base further comprises a nozzle assembling hole for assembling a nozzle, the nozzle being fixed inside the nozzle assembling hole, the nozzle comprising a check ring; wherein fluid in the central cavity and the nozzle is communicated through a hole and/or a pipeline penetrating through the central cavity and the nozzle. 